Circadian rhythm


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Circadian rhythm

  2. 2. The term "circadian", was coined by Franz Halberg
  3. 3.  The term circadian comes from two Latin words namely “circa” means around “diem/dies” means day Circadian means “approximately one day’’
  4. 4.  4th century BC - Androsthenes  13th century - The observation of a circadian or diurnal process in humans is mentioned in Chinese medical texts .  1729 - The first recorded observation of an endogenous circadian oscillation by the French scientist Jean-Jacques d'Ortous de Mairan
  5. 5.  1896 - Patrick and Gilbert observed that during a prolonged period of sleep deprivation, sleepiness increases and decreases with a period of approximately 24 hours.  1918 - J.S. Szymanski showed that animals are capable of maintaining 24-hour activity patterns in the absence of external cues.  1994 - Joseph Takahashi discovered the first mammalian 'clock gene' (clock) using
  6. 6. CIRCADIAN RHYTHM A 24-hour biological rhythm controlled by a “pacemaker” in the brain that sends messages to other systems in the body. Circadian rhythm influences various regulatory functions, including the sleep–wake cycle, body temperature regulation, patterns of activity such as eating and drinking, and hormonal and neurotransmitter secretion.
  7. 7. CIRCADIAN RHYTHM A circadian rhythm is any biological process that displays an endogenous, entrainable oscillation of about 24 hours. Although circadian rhythms are endogenous ("built-in", self-sustained), they are adjusted (entrained) to the local environment by external cues called zeitgebers, commonly the most important of which is daylight. (wikipedia)
  8. 8.  A zeitgeber is any external or environmental cue that entrains, or synchronizes, an organism's biological rhythms to the earth's 24-hour light/dark cycle and 12 month cycle Eg: ◦ Light ◦ Temperature ◦ Social interactions ◦ Pharmacological manipulation ◦ Exercise ◦ Eating/drinking patterns
  9. 9.  Zeitgebers induce changes in the concentrations of the molecular components of the clock to levels consistent with the appropriate stage in the 24-hour cycle, a process termed entrainment.
  10. 10. Biological markers The classic phase markers for measuring the timing of a mammal's circadian rhythm are:  melatonin secretion by the pineal gland  core body temperature
  11. 11. Effects of age on Circadian rhythm  Newborn baby -16 to 20 h  Child - 10 to 12 h  Age 10 - 9 to 10 h  Adolescence - 7 to 7.5 h  A gradual decline to about 6.5 h develops in late adult life.  35 years of age onward, women tend to sleep slightly more than men
  12. 12. CRITERIAS OF A CIRCADIAN RHYTHM To be called circadian, a biological rhythm must meet these four general criteria:  The rhythms repeat once a day (they have a 24- hour period).  The rhythms persist in the absence of external cues (endogenous).  The rhythms can be adjusted to match the local time (entrainable).  The rhythms maintain circadian periodicity over a range of physiological temperatures; they exhibit temperature compensation.
  13. 13. CIRCADIAN RHYTHM DISORDERS Circadian rhythm disorders occur when individuals attempt to sleep at times that are inconsistent with their underlying biological clocks.
  14. 14. CIRCADIAN RHYTHM DISORDERS  Intrinsic Circadian Rhythm Disorders. Delayed Sleep Phase Syndrome (DSPS) Advanced Sleep Phase Syndrome (ASPS) Irregular Sleep-Wake Pattern Non-24-Hour Sleep-Wake Syndrome  Extrinsic Circadian Rhythm Disorders Shift Work Time-Zone Change Disorders
  15. 15. Intrinsic Circadian Rhythm Disorders. Intrinsic circadian rhythm disorders refer to desynchronizes between attempts to sleep and the sleep-wake circadian rhythm that are due presumably to internal rather than external causes. These disorders might result from a weak circadian rhythm or from an inability to entrain the rhythm to the environment.
  16. 16. Delayed sleep phase syndrome  First identified by Weitzman et al. (1981) as a ‘‘chrono biological disorder with sleep-onset insomnia.’’  Sleep-wake circadian rhythm is delayed compared to the time the individual attempts to sleep  Individuals report difficulty falling asleep at a desired bedtime but have normal sleep if they attempt to sleep a few hours later.
  17. 17. Delayed sleep phase syndrome  Individuals with DSPS show late sleep onset, few awakenings, early wake-up times when work or social demands are present, and late (mid afternoon) wake-up times when there are no such demands on their time.  Delayed sleep phase individuals commonly identify themselves as „„night people‟‟ and report being most alert during the late evening and night hours.
  18. 18. Advanced sleep phase syndrome  Inability to stay awake until the desired bedtime and inability to remain asleep until the desired wake-up time.  Typical sleep onset times are between 6 P.M. and 8 P.M., and no later than 9 P.M., and wake times are between 1 A.M. and 3 A.M., and no later than 5 A.M.
  19. 19. Advanced sleep phase syndrome  ASPS is much more common in older individuals than in the young, and the complaint of waking up too early in the morning may be confused with depression.
  20. 20. Advanced sleep phase syndrome  The current approach to treating ASPS is bright light exposure in the evening and avoidance of light exposure (e.g. wearing dark, wrap around sunglasses) in the morning. Bright light exposure in the evening and the avoidance of bright light in the morning, it is thought, help to re entrain the sleep-wake cycle into the circadian rhythm.
  21. 21. Irregular Sleep-Wake Pattern  This rare disorder is characterized by a variable and disorganized sleep-wake pattern that suggests the absence of circadian rhythmicity.  Sleep is broken into several short sleep episodes, but the cumulative sleep for a 24- hour period is at normal levels.
  22. 22. Irregular Sleep-Wake Pattern  Polysomnographic studies show no abnormalities in sleep parameters except for the short duration of each episode.  Common in elderly people with dementia.  Treatment consists of a gradual decrease in the number and duration of daily naps. Increase in activity levels and social interaction is recommended to facilitate the process.
  23. 23. Non-24-Hour Sleep-Wake Syndrome  This is a disorder in which individuals are unable to entrain to a 24-hour day and instead maintain 25- to 27- hour sleep-wake cycles. Some individuals with this syndrome tend to progressively phase delay. The disorder is rare in the general population and is assumed to have higher prevalence among blind people.
  24. 24. Non-24 Hour Sleep-Wake Syndrome Other names  Non-24  Free running disorder (FRD)  Hypernychthemeral disorder  Circadian rhythm sleep disorder – free running type  Circadian rhythm sleep disorder – nonentrained type  Non-24-hour circadian rhythm disorder  Non-24-hour sleep-wake disorder
  25. 25. Non-24-Hour Sleep-Wake Syndrome  It is a chronic circadian rhythm sleep disorder, classified within Chapter VI, Diseases of the Nervous System, in the ICD 10.  It can be defined as "a chronic steady pattern comprising one- to two-hour daily delays in sleep onset and wake times in an individual living in society".  The pattern of delay persists literally "around the clock", typically taking a few weeks to complete one cycle.  This disruption of the body clock causes cyclical bouts of nighttime sleeplessness and excessive daytime fatigue and napping.
  26. 26. Non-24-Hour Sleep-Wake Syndrome  Treatment focuses on entraining the circadian rhythm to a 24-hour day through social interaction, exposure to light, and melatonin.  Melatonin has been successful in treating this disorder in blind individuals.
  27. 27. Extrinsic Circadian Rhythm Disorders  Shift Work  Time-Zone Change Disorders
  28. 28. Shift Work Disorder A disrupted sleep-wake schedule often results in disturbed and shortened sleep sleepiness on the job reduced performance levels psychological distress due to disruptions in family and social life.
  29. 29. Time-Zone Change Disorders
  30. 30. Time-Zone Change Disorders  Dyssomnia associated with rapid time-zone change (‘‘jet lag’’) is due to desynchrony between the endogenous sleep-wake rhythm and the light/dark cycle.  Symptoms include an inability to sustain sleep and excessive sleepiness.  For most people, these symptoms subside after a few days, depending on the number of time zones crossed.
  31. 31. Time-Zone Change Disorders  Frequent travelers, such as transatlantic airline crews, may experience more persistent difficulties.  Westward travel is associated with disturbed sleep at the end of the sleep period, which coincides with habitual wakeup time, and eastward travel is associated with sleep onset insomnia.
  32. 32. Time-Zone Change Disorders  Bright light treatment  Melatonin administration about an hour before bedtime in the new time zone
  33. 33. Risk Groups  DSP is more common in teens and young adults, occurring at a rate of 16 percent  ASP is more common as people age, occurring in about one percent of middle aged and older adults.  Irregular sleep-wake rhythm may occur in nursing home residents and other people who have little exposure to time cues such as light, activity and social schedules.
  34. 34. Risk Groups  Free-running (nonentrained) type occurs in more than half of all people who are totally blind.  Jet lag can affect anyone who travels by air, but symptoms may be more severe and may last longer in older people and when anyone travels in an eastward direction.  Shift work disorder is most common in people who work night shifts and early morning shifts
  35. 35. Effects  Sleep loss  Excessive sleepiness  Insomnia  Depression  Impaired work performance  Disrupted social schedules  Stressed relationships
  36. 36. TREATMENT OF CIRCADIAN RHYTHM DISORDERS  Behavior therapy or advice about sleep hygiene.  Avoid naps, caffeine, and other stimulants.  Bright light therapy  Blue blocking glasses therapy  Medications such as melatonin and modafinil (Provigil)  Tasimelteon has been proven effective in Phase III trials.  Sleep phase chronotherapy
  37. 37. TREATMENT OF CIRCADIAN RHYTHM DISORDERS  People who suffer from delayed sleep phase syndrome are generally unable to reset their circadian rhythm by moving their bedtime and rising time earlier.  In sleep phase chronotherapy, an attempt is made to move bedtime and rising time later and later each day, around the clock, until the person is sleeping on a normal schedule.
  38. 38.  Here's an example of how chronotherapy could work over a week's course of treatment, with the patient going to sleep 3 hours later every day until the desired sleep and waketime is reached. (Shifting the sleep phase by 3 hours per day may not always be possible; shorter increments of 1–2 hours are needed in such cases.)  Day 1: sleep 04:00 to 12:00  Day 2: sleep 07:00 to 15:00  Day 3: sleep 10:00 to 18:00  Day 4: sleep 13:00 to 21:00  Day 5: sleep 16:00 to 00:00  Day 6: sleep 19:00 to 03:00  Day 7 to 13: sleep 22:00 to 06:00  Day 14 and thereafter: sleep 23:00 to 07:00
  39. 39. NURSES RESPONSIBILITY  Obtain a thorough and careful sleep history both from patient and partner. Episodes of parasomnias and other sleep disorders are unrealized by the patient, but can be described in detail by the partner  Ask patient to maintain a sleep diary which include all sleep histories.  Maintain a regular and consistent bed time and wake time that is similar to both workdays and non-work days
  40. 40. NURSES RESPONSIBILITY  Develop a regular relaxing bed time routine about 1 to 2 hour before sleep onset.  Establish comfortable sleeping conditions most conducive to good sleep.(cooler room temperature, darkness, and low noise levels)
  41. 41. NURSES RESPONSIBILITY  Exercise regularly, but avoid vigorous exercise within 2 to 3 hours of sleep onset.  Spend some time outside each day.  Avoid exposure to bright light in the evening before bed and encourage exposure to bright light in the morning on
  42. 42. NURSES RESPONSIBILITY  Avoid stimulants such as stimulants in the evening.  Do not use alcohol to facilitate sleep initiation; this is likely to result in sleep fragmentation later in the night as blood alcohol levels fall.  Refer patient to a sleep specialists for diagnostic procedures like polysomnography actigraphy etc.